I support the point made about Final Fantasy. That genre tends to be one of the few where you see the "new setting/characters" theme while keeping the basic concepts. That was until this past decade, but we all know that Square-Enix was suffering from complications of terrible acid trips and irritable bowel syndrome. Still, it's held in high regard because the utter refusal to ape previous games was the series strong suit. That said, Dragon Quest, Atelier, Mana, Chrono, Persona (barring the Answer), and Star Ocean all had sequels with different settings, characters, and motivations. Looking outside that genre, Castlevania (to a lesser degree) seems willing to create, rather than pile on itself. Then again, that timeline is so screwed up at this point, having direct sequels (like Dawn of Sorrow) might be seen as novel.
Adam Sessler shares this viewpoint, calling it "sequel fatigue." Think about Assassin's Creed. It was a novel experience, but going through the motions every year (even with a different descendant) would seem ridiculous.